This invention relates generally to improvements in methods and apparatus for controlling dosimetry in the application of electric currents to a load and, more particularly, to a new and improved electrical dosimetry control system useful in the application of electric currents to a human body or the like, dosage being determined by the product of time and electrical current, wherein electrical current magnitude and/or time may be selectively varied by the patient or therapist during an administration procedure, to suit the comfort or convenience of the patient, without altering the total predetermined dosage to be administered. While the invention may be applied to dosimetry control in the application of electrical currents to any suitable load, it is particularly applicable to iontophoretic systems used for galvanic therapy and/or to infuse precise amounts of medication in applying electrical currents to the human body.
Around the turn of the century the art disclosed a plethora of electrode types for applying "electric treatments" to the human body. The electrodes were normally placed upon the body in relation to the position of an organ to be treated.
These "electric treatments" encompassed a wide range of applications. For example, galvanic (direct current) treatments have been popular in the past for their polar effects on ionized molecules, causing the ionized molecules to be driven through the skin, usually superficially. This phenomenon is known as iontophoresis or ion transfer, and it has been employed for the introduction of medicants, or even simply moisture, into the skin of a patient.
More specifically, some ions of zinc and copper can be employed in the treatment of some skin infections, and chlorine ions have been employed for the loosening of superficial scars. Further, vasodilating drugs can be used in rheumatic and peripheral vascular affections, and skin anesthesia can be produced by iontophoresis of local anesthetic drugs. It has been suggested that application of direct current to carefully selected areas of a living animal can produce anesthetic effects.
Although the above mentioned iontophoretic treatments have been found to be effective, some patients experience considerable discomfort when sufficiently high levels of electrical current are applied, and patient tolerance can vary widely. Previously, not much could be done to relieve patient discomfort other than to stop and start treatments until the necessary dose is ultimately applied. Of course, such procedures result not only in patient discomfort, but also in eratic and inaccurate dosimetry.
The aforementioned undesirable effects of iontophoretic treatment have resulted in a less than enthusiastic reception of iontophoretic techniques by the medical community in spite of the great and varied advantages to be realized through their use and development.
More specifically, in the application of electrical currents to the human body for therapeutic benefits, two variables affect the outcome of the treatment, i.e., the quantity of electrical current administered and the length of time the current is administered. Since each of these two variables act to offset each other during treatment, it has been an age old desire on the part of the practitioner to have some means of accurately measuring and controlling the composite or product of these two components as an indication of administered dosage. Furthermore, the result of this interaction of two distinct dosage determining variables must be consistently repeatable for reliable dosimetry.
Present technology measures time and current as two separate variable parameters and relies on the practitioner to interpolate the results with often great inaccuracy and little likelihood of replicating the treatment with precision. The present means of accomplishing this is to rely on an ammeter for electrical current readings and a suitable timing mechanism to indicate the duration of treatment. The variability comes about because, as previously indicated, no two patients have the same tolerance for electrical current and the practitioner is forced to vary the current according to patient tolerance. Moveover, patient tolerance can also vary considerably throughout treatment, necessitating continuous changes in electrical current levels. Keeping track of administered dosage, in the face of such complex variabilities, is a virtually impossible task.
Hence, those concerned with development and use of iontophoretic devices and the like in the medical field have long recognized the need for improved electrical dosimetry measurement and control systems which enable more accurate and reliable dosage administration to the patient, while simultaneously satisfying patient comfort requirements, all in a convenient device under the direct control of the patient, doctor, or therapist, and which also obviates the need for a high degree of skill or subjective expertise on the part of medical personnel or a patient attempting to reliably measure dosage. The present invention fulfills all these needs.